How do you get past bridge crossing in cool math

you get the man in the wheel chair (1) and the man in the yellow shirt (3) across the send the man in the wheel chair (1) back and send the man in the wheel chair (1) and the man in the suit (6) across then send the man in the wheel chair (1) back and send the old lady (12) and the girl in pink (8) across then send the man in the yellow shirt (3) back and then send the man in the wheel chair(1) and the man in the yellow shirt (3) back

you should end with 1 minute to spair :) <3